In video surveillance, for example, identifying a left-behind object and a person who stays in a place for a period of time longer than a certain time has been considered in recent years (see PTL 1, for example). In PTL 1, motion in a scene is analyzed at multiple time scales and long-term and short-term background models are compared with one another. This is used to differentiate among pixels that belong to primarily static background portions of the scene, pixels that belong to the active foreground portions, and pixels that belong to a left-behind object which has been static for some amount of time.
PTL 2 to PTL 6 also discloses related art.